Zoom Technology has been manufacturing transmission testing equipment since 1984. Our first product was an inexpensive lockup tester, the GM-1. Currently, Zoom manufactures the TranX 101, a high-tech, easy-to-use computerized shifter, and several other types of transmission testers. The following article provides an overview of testing methods, and introduces our newest entry into the transmission rebuilding industry, the TranX 2000.

When diagnosing a vehicle, you have three potential areas for problems: the transmission itself-the vehicle's ECU- and peripheral components, including harnessing. It's not unusual to find problems in more than one area, because transmission problems tend to ripple.

To test and troubleshoot a vehicle, you need the ability to isolate the transmission from the ECU. At times, you also need to look at everything together. Figure one illustrates the 3 possible approaches to testing.

Figure 1a

Figure 1b

Figure 1c

Scanner Method
The ability to retrieve codes is critical in repairing today's sophisticated vehicles. Most shops have already invested in scanners and are using this method regularly to diagnose problems. While there are some people out there who will tell you a scanner is all you need, most will agree that there are times when a scanner is simply not enough.

Without a doubt, a scanner is a very useful tool-but you can't bench test with one, and what do you do when it's the ECU that's broken and you can't use the scanner?

Isolation Method (Shifter)
The Isolation Testing Method uses a shifter to replace the ECU and drive the transmission. You can see from figure one that the shifter approach separates the transmission from everything else. The vehicle becomes a Dyno when you use this method to diagnose problems-because you've eliminated the vehicle's computer and harness from the picture. This approach is effective when you are looking for electrical, hydraulic or mechanical problems in the transmission. In fact if you look at any modern dyno or valve body test system, they include a shifter.

What are the pitfalls of Isolation Testing? You have rebuilt the transmission and feel you are home free. The biggest problem is that finally at some point you have to reconnect the transmission to the system. What if the system still doesn't work? You know the transmission is okay, right? Now what's next? Of course you can fall back to your scanner, but it may be a bad connection, so you get out the multimeter and root around. You could send the customer up the street to have the system fixed-they'll really like that! So what do you do? Well, how many hours do you have?

The Shifter/Monitor approach connects to the transmission case and engine harness. You are focused at the business end of the system and can quickly analyze the transmission both as a component and as part of the overall system. By adding a scanner, you can check the ECU and overall system health. Some of the newer vehicles can actually be shifted using the scanner and, with the monitor in place, you can observe the electrical signaling between the ECU and transmission.

Introducing the TranX 2000 Transmission Analyzer
The TranX 2000 (a shifter/monitor) is the culmination of several years' experience serving the transmission rebuilding industry. Our goal for this unit was to provide a simple, easy-to-use tester that would be adaptable to every electronic transmission. We wanted a tester that could either manually shift the transmission, or monitor the vehicle's computer as it shifts the transmission. We also wanted a tester that could be used as a companion tool with a scanner. Most importantly, we wanted a product that would help you find the problems fast!

Here's how the TranX 2000 works:

The TranX 2000 operator controls are divided into five functional sections: Transmission code selection, test mode, transmission control and monitoring, sensor monitoring and solenoid monitor/multimeter (Figure 2). This simple and orderly placement of controls makes learning to use the TranX 2000 easy. The same testing app-roach is used for each transmission type. This really makes the TranX easy to learn and easy to use. It also makes it universal!

Transmission Code Selection (Figure 2)
We use a simple three digit code to identify the vehicle/transmission you're going to test -the codes are all listed in our instruction manual. Identify the transmission, look up the code, and punch it in-it's that simple!

Figure 2a-Select Code

Test Mode (figure 2)
The TranX can perform four types of tests. To select the test you want, push the test mode button: An LED lights as you select each test.

Figure 2b-Test Mode

Here is a summary of what each test will accomplish:

• Test solenoids - This test mode allows you to select each solenoid individually and to test it quickly. Select solenoids using the Gear Up/Down switches. You can measure solenoid current, solenoid resistance and solenoid voltage quickly and efficiently. Perform this test with the engine off-or on the bench, if you need to.
• Drive Transmission - Start the Engine! In this mode the TranX 2000 becomes a shifter. The vehicle's computer automatically disconnects from the transmission and the TranX will now shift the transmission. All shifting information was programmed when you entered the select code. You are in control of functions such as lockup, coast clutch and underdrive. Two identical -Duty controls let you make precise adjustments within 1% duty cycle. Need to know what's happening? You can read solenoid current, solenoid resistance and solenoid voltage, either individually or all together. Test points and bicolor LEDs also allow sensor outputs to be tested.
• Monitor Vehicle Computer - In this mode, the TranX 2000 automatically becomes a monitor. You'll see decoded signals being sent by the vehicle's computer as well as the gear called for by the computer. Both duty cycle displays actively display the percent duty cycle the ECU is calling for. The TranX 2000's digital multimeter and bicolor LEDs help you quickly discover missing or weak signals from the vehicle's computer harness to the transmission. Sensor information displays continuously from the sensor module. Is something else in the engine system bad? You can monitor with the TranX and operate your scanner simultaneously. How's that for getting the full picture?
• Special - This mode is for special tests, unique to the transmission system.

Transmission Control Seven Monitoring (figure 2)
This section of the TranX 2000 contains the switches and displays that control the transmission. This section has three parts.

Figure 2c-Transmission Control & Monitoring

• Gear - A one-digit display indicates the gear called for. The display also indicates the solenoid selected in the Test Solenoid mode. The up and down switches select the gear or solenoid.
• Functions - Five switches activate special functions such as lockup, coast clutch, 4WD, etc. The switches are push on/push off and have an LED to indicate when they are on.
• Function % Duty - A two-digit display indicates duty cycle (percentage of on-time). An application for this function would be the 4L60E 3-2 solenoid, which changes duty cycle. It also pulses from 90% to 30% on a 3-2 shift. The up and down keys can be single-pushed, for 1% increments, or held in, for fast-counting increments. Push the center Max/Min key along with the up or down key to move to either end of the scale.
• Pressure % Duty - Use this display for transmissions having electronic line pressure control. General operation of the display and up/down controls are the same as above.This test is especially useful when you're using a line pressure gauge. The fine, 1% resolution allows you to evaluate the EPC solenoid carefully!
• Sensor Monitoring (figure 2)- The sensor module monitors up to eight transmission sensors. Eight bicolor LEDs are used-here's what they indicate:
• Red = positive voltage
• Green = ground
• Orange = pulsing
• Off = floating

Figure 2d-Sensor Monitoring

Need more accuracy? Each sensor has a test point which you can plug in a scope, multimeter or frequency meter, neatly and conveniently. And we have an eye on the future, too - the sensor module can be changed, so that, as your needs evolve, we can provide other modules.

• Solenoid Monitor/Multimeter - The TranX 2000 has one of the most complete and comprehensive solenoid monitoring capability of any product available today. We measure the voltage at each solenoid connection as well as the current to each solenoid, and we can calculate the resistance of each solenoid! We can do this while driving the solenoid or while it is being driven by the vehicle's ECU! Ever have to chase a bad connection with a digital multimeter, or try to see quickly what is happening when you have an intermittent condition? Wait till you see how quickly you can do it now!
• Digital Multimeter - The upper part of this section contains two displays and two switches. The top display is a two-digit display and can display amps, volts or ohms. Three small LED arrows point at the appropriate selection. Each time you push the Amps/Volts/Ohms switch, the arrow moves.
• Directly below the top display is the four-output switch. The four-output switch electronically moves the digital multimeter to the different solenoid outputs.

Figure 2e-Solenoid Monitor/Multimeter

The Lower display is a one-character LED and will display A for all outputs (for total current, total average voltage, or total ohms). Zero through nine displays for individual solenoid outputs.

The digital multimeter is active in all modes. If, for instance, you think you have a bad connection in the shift solenoid two circuit, all you have to do is measure the current or voltage for output two. It's that easy!

Solenoid Indicators
The lower half of this section provides both test points and bicolor LEDs for monitoring each of the 10 TranX solenoid driver circuits. The LEDs indicate the state of the solenoid circuit and are red for positive voltage, green for ground, orange for pulsing and off for floating. There are test points for each solenoid, as well as battery positive and battery negative.

Hook Up
When we designed the TranX 2000 we had a couple of key objectives:

• Compatibility - the TranX 2000 uses the same cables to the transmission as the TranX 101 - so TranX 101 owners can upgrade economically.
• Lead lengths as short as possible - to eliminate power losses.
• Flexible cabling - reduces the size of the cable from the transmission to the inside of the car.

After studying the problem, we decided to separate the controls and displays from the switching and driving circuits. This enabled us to run short, heavier cable between the transmission and computer harness and thinner, more flexible cable to the tester.

As you can see from the photo, we actually use two separate cables to shift and monitor. If the unit is used as a shifter, you can leave off the monitor cable. This makes things neater for bench testing. Also, we have two ways to apply power to the TranX 2000: We can plug the lighter cable into the TranX 2000 in the car or into the TranX 2000 switch box under the hood. This feature makes using your scanner with the TranX 2000 easier.

At the time of this article, we have 35 different adapter sets available and expect to complete several others by the end of the year. Adapters are available for most domestic, Asian and European vehicles. All adapters are clearly marked with part numbers and application.